At the intermediate level, si handles almost every conditional need. But advanced Spanish uses a whole family of conditional connectors — siempre y cuando, a condición de que, con tal de que, a menos que, a no ser que, en caso de que — and every single one of them demands the subjunctive. This page covers each connector, explains its specific shade of meaning, and shows you when to reach for it instead of plain si.
The golden rule: they all take subjunctive
Before we look at individual connectors, internalize this: every conditional connector in Spanish other than si triggers the subjunctive. No exceptions. The reason is that these connectors all frame the condition as hypothetical, uncertain, or contingent — exactly the territory the subjunctive was designed for.
Te ayudo si me lo pides. (indicative after si)
I'll help you if you ask me. (si + indicative for open conditions)
Te ayudo siempre y cuando me lo pidas. (subjunctive)
I'll help you as long as you ask me.
Siempre y cuando: "as long as" (the strict condition)
Siempre y cuando sets a firm condition: the main action will happen only if the condition is met. It is slightly more emphatic than si — it underlines that the condition is non-negotiable.
Puedes salir esta noche siempre y cuando termines la tarea.
You can go out tonight as long as you finish your homework.
Estamos dispuestos a negociar, siempre y cuando se respeten nuestros derechos.
We are willing to negotiate, as long as our rights are respected.
Te presto el carro siempre y cuando lo devuelvas con tanque lleno.
I'll lend you the car as long as you return it with a full tank.
Siempre y cuando is common in both spoken and written Spanish. It is slightly more formal than si, but not so formal that it sounds out of place in conversation.
Siempre que: "as long as" or "whenever" (the ambiguous one)
Siempre que is a chameleon. With the subjunctive, it means "as long as" (conditional). With the indicative, it means "whenever" or "every time" (temporal).
Conditional reading (subjunctive)
Siempre que estudies, vas a aprobar.
As long as you study, you'll pass.
Temporal reading (indicative)
Siempre que voy a ese restaurante, pido lo mismo.
Whenever I go to that restaurant, I order the same thing.
Siempre que la veo, me sonríe.
Every time I see her, she smiles at me.
A condición de que: "on the condition that" (formal)
A condición de que is the most formal of the group. It appears in contracts, negotiations, and academic writing. In casual speech, it sounds overly stiff.
Aceptaré el puesto a condición de que me ofrezcan un salario justo.
I will accept the position on the condition that they offer me a fair salary.
El acuerdo se firmará a condición de que ambas partes estén de acuerdo.
The agreement will be signed on the condition that both parties are in agreement.
When the subject of both clauses is the same, you can use the infinitive: a condición de + infinitive.
Acepto a condición de recibir un salario justo.
I accept on the condition of receiving a fair salary.
Con tal (de) que: "provided that, so long as"
Con tal de que (sometimes con tal que, without the de) expresses a condition that the speaker considers the minimum required. It often implies willingness or eagerness: "I'll do X — all I need is Y."
Hago lo que sea con tal de que mis hijos estén bien.
I'll do whatever it takes provided that my children are well.
Te perdono con tal de que no vuelva a pasar.
I forgive you provided that it doesn't happen again.
Con tal de no trabajar los domingos, acepto cualquier horario.
As long as I don't have to work Sundays, I'll accept any schedule.
The last example uses con tal de + infinitive (same subject in both clauses).
A menos que: "unless"
A menos que is the standard way to express "unless" in Spanish. It always takes the subjunctive because the condition it introduces is presented as contrary to the expected course of events.
Vamos a salir a menos que llueva.
We're going out unless it rains.
No voy a cambiar de opinión a menos que me presentes evidencia nueva.
I'm not going to change my mind unless you present new evidence.
El vuelo sale a las ocho, a menos que haya retrasos.
The flight leaves at eight, unless there are delays.
A no ser que: "unless" (slightly more formal)
A no ser que means the same as a menos que but sounds slightly more formal or literary. In everyday Latin American Spanish, a menos que is more common; a no ser que is frequent in written Spanish and in Spain.
Llegaremos a tiempo, a no ser que el tráfico esté muy mal.
We'll arrive on time, unless the traffic is really bad.
La reunión sigue en pie, a no ser que alguien tenga una objeción.
The meeting is still on, unless someone has an objection.
En caso de que: "in case"
En caso de que introduces a precautionary condition — it prepares for a possible future scenario. It is close to English "in case" or "in the event that."
Lleva un paraguas en caso de que llueva.
Take an umbrella in case it rains.
En caso de que necesites ayuda, llámame.
In case you need help, call me.
Dejé comida en el refrigerador en caso de que llegaras tarde.
I left food in the fridge in case you got home late.
Notice the imperfect subjunctive llegaras in the last example — because the main verb is in the past (dejé), the subjunctive shifts to the imperfect.
When the subject is the same, you can use en caso de + infinitive:
En caso de necesitar algo, no dudes en preguntar.
In case you need something, don't hesitate to ask.
Complete reference table
| Connector | English | Mood | Register | Key nuance |
|---|---|---|---|---|
| si | if | Indicative (open) / Imperfect subj. (contrary-to-fact) | All | The default conditional |
| siempre y cuando | as long as | Subjunctive | All (slightly formal) | Non-negotiable condition |
| siempre que | as long as / whenever | Subjunctive (conditional) / Indicative (temporal) | All | Ambiguous: mood determines meaning |
| a condición de que | on the condition that | Subjunctive | Formal | Contracts, negotiations |
| con tal (de) que | provided that | Subjunctive | All | Minimum requirement / willingness |
| a menos que | unless | Subjunctive | All | Exception to the expected outcome |
| a no ser que | unless | Subjunctive | Slightly formal | Same as a menos que, more literary |
| en caso de que | in case, in the event that | Subjunctive | All | Precautionary / preparatory |
Infinitive alternatives (same subject)
When the subject of the condition clause and the main clause is the same person, several of these connectors allow you to drop the que and use an infinitive instead:
A condición de que aceptes → A condición de aceptar (same subject)
On the condition that you accept → On the condition of accepting
Con tal de que no pierdas el vuelo → Con tal de no perder el vuelo (same subject)
Provided that you don't miss the flight → Provided you don't miss the flight
En caso de que necesites algo → En caso de necesitar algo (same subject)
In case you need something → In case of needing something
A menos que and a no ser que do not normally take infinitive constructions — they almost always appear with a conjugated subjunctive verb.
Common mistakes
❌ Vamos al parque siempre y cuando no llueve.
Wrong mood: siempre y cuando always takes subjunctive.
✅ Vamos al parque siempre y cuando no llueva.
Correct: llueva (present subjunctive).
❌ Te ayudo a menos que no me pides.
Double error: wrong mood and unnecessary double negative.
✅ Te ayudo a menos que no me pidas.
Correct: pidas (subjunctive). Note: the 'no' is acceptable here for emphasis.
❌ En caso de que necesitas ayuda, llámame.
Wrong mood: en caso de que takes subjunctive.
✅ En caso de que necesites ayuda, llámame.
Correct: necesites (present subjunctive).
❌ Acepto el trabajo con la condición de que me pagan más.
Wrong connector form and wrong mood.
✅ Acepto el trabajo a condición de que me paguen más.
Correct: a condición de que + subjunctive.
For the basics of si clauses, see Conditional Conjunctions. For conditional sentence types, see Type 1 Conditionals. For the subjunctive in adverbial clauses of condition, see Subjunctive: Adverbial Condition.
Related Topics
- Conditional: Si, A menos queB1 — How to build conditional clauses with si, a menos que, con tal de que, and other condition conjunctions.
- Type 1: ProbableB1 — Use a present-tense si-clause with a future, imperative, or present result clause for situations that are likely to happen.
- Adverbial: Condition (A menos que, Con tal de que)B2 — Conditional conjunctions that always trigger the present subjunctive in Spanish.
- Correlative and Parallel Conditional StructuresC1 — Formal alternatives to si clauses — de + infinitive, a + infinitive, con + infinitive, and other conditional patterns.